1. Field of Invention
The present invention is related to systems and methods for chemical and biological analysis and, in particular, to systems, apparatus, and methods of sample conditioning and analysis involving subjecting samples to constant or alternating high hydrostatic pressure in the presence of an electromagnetic fields in order to monitor sample response by means of induced radio frequency electromagnetic signals in the MHz to GHz range.
2. Discussion of Related Art
Magnetic resonance spectroscopy allows understanding of molecular structure and interactions. Electron Paramagnetic Resonance spectroscopy (EPR), alternatively called Electron Spin Resonance spectroscopy (ESR), is playing a unique role in the investigation of chemical and biological sciences. EPR is a technique that is applicable to systems in a paramagnetic state or which can be placed in such a state. Examples:
1. Free radicals in the solid, liquid or gas phases.
2. Transition ions including actinide or lanthanide ions.
3. Various point defects (e.g., An electron trapped at a negative ion vacancy in crystals and glasses or deficiency of an electron, i.e., a positive hole).
4. Systems with more than one unpaired electron (e.g., Triplet-state systems, biradicals, etc.).
5. Systems with conducting electrons (e.g., semiconductors, metals).
Therefore, sample containers suitable for EPR must not contribute significantly to the paramagnetic properties of the sample, thus limiting the choices for materials used to make said containers from. For example, metal containers of any kind are unacceptable for EPR spectroscopy. On the other hand, materials typically used to sustain high levels of hydrostatic pressure (e.g. metals) are likely to possess strong paramagnetic or ferromagnetic properties, incompatible with EPR.
Furthermore, it is desirable to separate the liquid sample from the pressure media fluid. If a sample filled cell is directly connected with the fluid in the high pressure generator, the two fluids can mix and confuse the measurement. Thus only direct pressure communication is desirable but not direct fluid communication.
Wand et al. (U.S. Pat. No. 6,362,624B1) teaches that a NMR cells made from “zirconium oxide” or “quartz” that holds samples under modest pressure. Wand shows a maximum pressure of 14,000 psi and he does not show the dimensions needed to achieve and sustain such pressures. This application shows that containers manufactured from ordinary zirconium oxide material are incapable of holding pressure in excess of 40,000 psi. Furthermore, the mounting method taught by Wand will release the full energy content of the pressurization system into the test chamber if the sample containing tube breaks. The release of a large amount of high pressure energy due to sample tube failure could damage the sensitive instrument in which the sample is positioned.